Control system for double-burner single-cavity oven



L. C. BIGGLE Nov. 4, 1969 CONTROL SYSTEM FOR DOUBLE-BURNERTSINGLB-QAVIIY OVEN Filed Nov. 15, 1967 3 Sheets-Sheet I;

INVENTOR A. c 5/6646 AT7UZA/EV Nov. 4, 1969 L. c. BlGGLE 3,476,315

CONTROL SYSTEM FOR DOUBLE-BURNER SINGLE-CAVITY OVEN Filed NOV. 15, 19673 Sheets-Sheet Z .526. .5. 4. :1 a/ife CAVITY OVEN L. C. BIGGLE Nov. 4,1969 CONTROL SYSTEM FOR DOUBLE-BURNER SINGLE- 3 Sheets-Sheet 3 FiledNov. 15, 1967 .R V) O w m I E 1 .9 mm 1. m a, m A 4 v. 5 1: a; \H 7 \f 1J W |\P llilllilllO United States Patent O 3,476,315 CONTROL SYSTEM FORDOUBLE-BURNER SINGLE-CAVITY OVEN Laurence C. Biggle, Pasadena, Calif.,assignor to International Telephone and Telegraph Corporation, New

York, N.Y., a corporation of Maryland Filed Nov. 15, 1967, Ser. No.683,400 Int. Cl. F23n 1/00; Gd 23/00; F24c 3/00 US Cl. 236-45 5 ClaimsABSTRACT OF THE DISCLOSURE The invention relates to the control ofheating units found in ovens, and in particular to a single controlsystem utilizing a single selector assembly for controlling multipleheat generating units in a single-cavity oven.

BACKGROUND OF THE INVENTION Technological progress has affected almostevery segment of our lives. The apparatus on which and in which our foodis prepared is no exception. Thus, in the recent past, conventionalcooking apparatus included essentially merely a single range, eithergas-fired or electric, provided with a single or double oven, and amultiplicity of heat generating elements arranged on a flat surface forsurface cookery. Indeed, this surface arrangement of heat generatingunits gave rise to the name range. Progress in this area has notinvolved major innovations in the basic heating units per se, butconsiderable innovation has occurred in the control mechanisms utilizedto facilitate use of the basic heating units, One major innovation thathas occurred in the design of cooking apparatus involves the separationof the conventional oven from the surface-cooking range. These units aremodernly of the built-in type, with the cooking surface or range beingbuilt into a convenient counter and the oven being built into aconvenient wall. Both of these units are arranged with respect to otherappliances in the modern kitchen to facilitate the use and lighten theburden for the homemaker.

These innovations are due in part to the desire of architects to achievean aesthetic effect in the kitchen which is in tune with the decorativescheme throughout the home. In this regard, oven units have beenrecessed in walls paneled with expensive hardwoods or covered withceramic tile. Achievement of the aesthetic effect has required thatcontrol mechanisms for such oven units be unobtrusive yet readilyavailable for manipulation by the homemaker. Additionally, at leastwhere the oven is gasfired, it is important the control mechanismincorporate built-in safety features with which the homemaker need notbe concerned when she manipulates the control.

Accordingly, it is one of the important objects of the present inventionto provide a control system for an oven utilizing multiple heatgenerating units as a main burner and a broiler burner of a controlsystem for controlling all of the burners or heat generating unitswithin the oven through manipulation of a single selector assembly.

In ovens that utilize gas to effect heating thereof, it is desirablethat the volume of gas be regulated in accordance with a predeterminedtemperature setting. In addition, it is desirable that the main andbroiler burners be ignited through use of an effective pilot. Pilots maybe of two types, Le, a standing pilot which is controlled by a separatevalve and once ignited remains lighted, and a pilot which iselectrically ignited each time it is desired to ignite the main orbroiler burner. It used to be that standing pilots were continuouslyactivated in that the source of gas for the pilot was not interrupted inthe ice event the pilot was extinguished. Modernly, safety devices areincorporated in conjunction with the pilot which will effect automaticcut off of the main source of fuel in the event the pilot isextinguished. It is therefore another object of the invention to providea control system utilizing a single assembly which when manipulatedactivates either an electric igniter which ignites the pilot, or whichis effective to channel fuel from an appropriate source to whateverburner is selected for ignition by a standing pilot. This singlemanipulation of a single selector assembly is also effective to set orto actuate a plurality of switches effective to activate solenoidvalves, monitor temperature and energize control circuits.

The invention possesses other objects and features of advantage, some ofwhich, with the foregoing, will become apparent from the followingdescription and drawings. The invention is not limited to the showingmade by said description and the drawings, since variant forms of theinvention may be adopted within the scope of the appended claims.

SUMMARY OF THE INVENTION In terms of broad inclusion, the inventioncomprises a single cavity oven-type cooking unit, either detached from arange-type unit, or in conjunction therewith, and equipped with a mainor roasting burner and an auxiliary or broiling burner. It is intendedthat the term burner will include a heat generating unit energized withelectricity. In the gas-fired type of appliance, each burner isassociated with a gas-fired pilot which is effective to ignite the gasdischarged from the main or auxiliary burner when one of these is turnedon. Associated with each of the pilots, is a pilot generator whichcomprises a thermocouple having a section exposed to the heat from thepilot and which generates an electric potential and current utilized tomaintain in an open condition the main gas supply valve for theappliance. Also, within the oven cavity, is provided a heat sensing unitin association with an adjustable control circuit for controlling theultimate temperature within the oven cavity. Interposed between each ofthe burners and the main gas supply valve is a single selector assemblyincluding a knob adapted for manipulation by the homemaker in selectingone or the other of the main or auxiliary burners within the ovencavity. This single selector assembly is constructed so that the singlemanipulation to choose one or the other of the main or auxiliary burnerswill control all other functions that need be controlled in conjunctionwith the burner selected.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective viewillustrating the multiple selectively energizable heat generating unitswithin an oven cavity in conjunction with the control mechanism forcontrolling such heat generating units.

FIG. 2 is a schematic illustration partly diagrammatic showing upper andlower burner assemblies in conjunction with a single control systemarranged for manipulation by a single selector assembly. The controlsare represented in the position they would assume when the upper burneris activated.

FIG. 3 is a schematic illustration in the nature of a cross-sectionalview through the selector assembly indicating the interconnection of gaspassages.

FIG. 4 is a view similar to FIG. 2 but showing the control system setfor activation of the lower burner assembly.

FIG. 5 is a schematic view in the nature of a crosssectional viewthrough the selector assembly indicating the interconnection of gaspassages when the selector assembly is set as in FIG. 4 to activate thelower burner assembly.

FIG. 6 is a schematic view partly diagrammatic, illustrating the dualburner system set in the OFF position of selector assembly.

FIG. 7 is a schematic view in the nature of a crosssection through theselector assembly indicating the position of the passages in the OFFposition of the selector assembly.

FIG. 8 is a schematic assembly view partly diagrammatic, illustratingthe dual burner system and single control system in conjunction with theelectromagnetic ally controlled main gas supply valve.

FIG. 9 is a schematic view similar to FIG. 8 but illustrating each ofthe pilot burners in association with an electric ignition system whichforms a part of a single control system and which is activated bymanipulation of the single selector valve.

DESCRIPTION OF THE PREFERRED EMBODIMENT In terms of greater detail, andreferring specifically to FIG. 1, the control system of the invention isembodied in an oven designated generally by the numeral 2, having acavity 3 within which are positioned a first main or roasting burner 4,conveniently of the gas-fired type, and a second main or broiler burner6, preferably of the same type. The multiple burner assembly iscontrolled from a single selector assembly 7 which is illustrated as athree-way valve in FIGS. 8 and 9. Assembly 7 is interposed between theburners and a normally closed safety valve 8. An appropriate conduit orfirst outlet 9 connects the selector assembly with the lower burner,while an appropriate conduit or second outlet 12 connects the upperburner with the selector assembly. The selector assembly is providedwith a selector knob or control means 13 adapted for manipulation by thehomemaker to select one or the other of the burners. The main gas supplyvalve is preferably of the magnetically controlled type, and isconnected to a source of gas through a main inlet conduit 14.

While selection of a particular burner within the oven cavity isdetermined by the homemaker upon manipulation of the selector knob toactivate either the lower or the upper burner, the temperature withinthe oven is controlled through appropriate thermostatic means includinga spring-biased control switch 16, adjusted by a knob 17, which in FIG.1 is illustrated as being a separate entity from the selector knob 13,but which in actuality is preferably incorporated in the same selectorassembly 7 and activated or set by manipulation of the selector knob 13.The switch mechanism operates in conjunction with a heat sensing elementor probe 18 which may conveniently be of the bulb-type that relies onthermoexpansion of a fluid to actuate the spring-loaded switch mechanism16. The switch mechanism 16 is connected by a pair of leads 19 and 21 tothe electromagnetically controlled main gas supply valve for operationin a manner which will hereinafter be explained in greater detail.

Operatively associated with the main or roasting burner 4 is a firstpilot burner 22, connected by a conduit 23 to an outlet port in theselector assembly 7 as illustrated in FIG. 1. The pilot 22 operates inassociation with an electric igniter activated through a lead 24 inresponse to manipulation of the selector knob to effect activation ofthe main burner. Such manipulation of the selector knob automaticallyactuates the movable blade of appropriate switch and valve mechanisms 37and 48 within the housing, illustrated best in FIG. 9.

In the same manner, the upper burner 6 is ignited by a second pilotburner 26, connected to the selector assembly through a conduit 27, and,where electric ignition is provided, ignited through manipulation of theselector knob as previously described. A control circuit is providedconnecting the electric ignition mechanism28 for both pilots (FIG. 9)with appropriate contacts 37 within the selector assembly body.

In any control system for gas-fired apparatus, it is essential that theON and OFF functions of the gas system be precisely controlled. In theapparatus illustrated, such control is effected through the use of firstand second thermocouples 29 and 30, associated respectively with theupper and lower pilots 22 and 26. Each of the thermocouples areconventional. The current generated is channeled through a controlcircuit including leads 31 and 32, connecting the pilot generators 29and 30, respectively, with an appropriate selector switch includedwithin the selector assembly 7. Such a switch is illustratedschematically in FIGS. 2, 4, 6, 8, and 9 and is designated generally bythe numeral 33.

For a more detailed description of the specific constructional aspectsof one form of the selector assembly, reference is made to copendingapplication Ser. No. 627,018, entitled Range Control System, filed inthe name of Richard D. Grayson and Le Roy Newton, and assigned to theassignee of the instant invention, now US. Patent No. 3,405,869 issuedon Oct. 15, 1968.

Referring to FIG. 2, in this schematic and diagram rnatic illustrationof the control system, the heat responsive switch means 16 has beenshown apart from the selector knob 13 on selector assembly 7. It shouldbe understood that these two elements of the combination are preferablycontrolled through a single actuator shaft illustrated schematically inFIGS. 2, 4, and 6 by the dash line 36. By the same token, the singlepole-double throw switch 33 is also preferably mounted to be actuated byrotary movement of the shaft 36.

In operation, starting from the OFF position illustrated in FIGS. 6 and7, clockwise rotation of the shaft 36 by manipulation of the selectorassembly knob will effect activation of the lower burner 4, by bringingthe main gas supply conduit into communication with the conduit 9leading to the lower burner. This condition is represented schematicallyin FIG. 5. Such rotation of the shaft will also shift the movable bladeof the single pole double throw switch 33 from the position shown inFIG. 6 to the position illustrated in FIG. 4. In the embodimentillustrated in FIG. 9, where each of the burners 4 and 6 is associatedwith a pilot equipped with an electric ignition system, rotation of theshaft 36 by manipulation of the selector assembly control knob 13 willalso effect closing of the ignition contact switch 37 so as to create anarc 38 as shown in close proximity to the pilot assembly 22, and thusignite the gas escaping therefrom. In the assembly illustrated in FIG.2, where the main burner utilizes a standing pilot the electric ignitionsystem is of course omitted. This arrangement is illustrated in FIG. 8.

If it is now desired to switch from the main burner, as illustrated inFIG. 4, to the broiler burner as illustrated in FIG. 2, the selectorassembly knob 13 is rotated counterclockwise so as to open a passagebetween the main gas supply line and the pilot 26, illustratedschematically in FIG. 3 by interconnection of the passages as shown, andof course connects the main supply line 14 with the conduit 12 to supplygas to the burner 6. Coincidentally, the supply of gas is also connectedto a reignition or auxiliary pilot 41 as shown best in FIG. 2.Manipulation of the selector knob to select broiler burner 6coincidentally actuates the single pole-double throw switch 33 so as tocomplete the circuit through lead 32 between the pilot generator 30 andthe electromagnetically controlled main valve 8. Thus, so long as thepilot generator is heated by the pilot, a solenoid winding 42 (FIGS. 8and 9) is energized, the spring-biased armature 43 is held in its lowerposition as shown in these two figures, and the valve member 44 isretained separated from valve seat or inlet 46 to permit passage of gasfrom the chamber within the electrically controlled valve assembly intothe selector assembly 7 as shown. Where the auxiliary or broiler burneris equipped with a pilot that requires ignition each time the burner isignited, appropriate manipulation of the ignition contact switch 37activates the ignition control system and strikes an are as at 47 toignite the gas permitted to escape from the pilot 26 by opening of valve49. In this regard, and with special reference to FIG. 9, where theselector assembly and control system includes an electric ignitionsystem, the selector assembly is provided with pilot valves 48 and 49,activated mechanically or electromagnetically through rotation of theshaft 36 by manipulation of the selector knob 13. In FIG. 9, pilot valve49 is shown in its open position so as to permit the passage of gas fromthe main gas valve through conduit 27 to the pilot 26. It should benoted that the electric ignition contact switch 37 is preferablyactuated against a spring pressure by rotation of shaft 36 so that thecontacts return to an open position immediately upon release of thecontrol knob 13. In this manner the ignition system to the associatedpilot is inactivated as soon as the pilot has ignited.

If desired, means may be provided to electrically ignite the standingpilots. Such ignition may be effected by counterclockwise rotation ofthe shaft 36 to a position indicated on the selector assembly as pilotignition, in which position the rotation of the shaft will effectclosing of appropriate contacts to momentarily energize the ap propriateignition system circuit. Thereafter, the standing pilot remains lightedas previously discussed.

What is claimed is:

1. In fuel burning apparatus, the combination comprising: first andsecond main burners; first and second pilot burners adjacent to saidfirst and second main burners, respectively; first and second outlets; athree-way valve having first and second inlet conduits for said firstand second outlets, said first and second outlets being connected,respectively, from said first and second inlet conduits, said three-wayvalve having an inlet, said three-way valve having control meansselectively operable to provide communication between said three-wayvalve inlet and of one said outlets at a time; a main inlet conduit; anormally closed safety valve connected between said main inlet and saidthree-way valve inlet; a solenoid winding; an armature adjacent saidwinding movable in response to energization of said winding to hold saidsafety valve open; first and second thermocouples adjacent said firstand second pilot burners, respectively, positioned to be heated thereby;and a selector switch movable in response to movement of said controlmeans for connecting first thermocouple in a manner to energize saidwinding when said control means is in a position providing communicationbetween said three-way valve inlet and said first outlet, and forconnecting said second thermocouple in a manner to energize said windingwhen said control means is in a position providing communication betweensaid three-way valve inlet and said second outlet, said selector switchbeing adapted to disconnect each one of said thermocouples from saidwinding when the other one is connected thereto.

2. The invention as defined in claim 1, wherein said safety valveincludes a spring to bias said armature to a valve closing position.

3. The invention as defined in claim 1, wherein at least one of saidmain burners includes a probe to detect the temperature therearound, anda normally closed control switch connected in series with said selectorswitch to open the circuit thereto when the temperature of said probeexceeds a predetermined magnitude.

4. The invention as defined in claim 3, wherein said control switch hasa spring to bias it closed.

5. The invention as defined in claim 4, Where said safety valve includesa spring to bias said armature to a valve closing position.

EDWARD G. FAVORS, Primary Examiner US. Cl. X.R. 1 26-39

